Approximately 25% of US teens are physically, psychologically, or sexually abused by dating partners each year. Victims of dating violence experience a host of devastating consequences, including acute and chronic mental and physical health problems, suicide, delinquency, risky sexual behavior, substance abuse, and school failure. Moreover, individuals who perpetrate violence and sexual aggression in their adolescent relationships are at a heightened risk for continuing this behavior in their adult intimate relationships. Preventing this form of violence would not only improve the health and lives of adolescents, but it would have the potential to curb the prevalence and consequences of subsequent domestic violence. Despite these critical needs, theoretically driven and research-based prevention programs are conspicuously lacking, and the factors that increase or decrease the likelihood of adolescents experiencing dating violence are poorly understood. In addition, few data exist on how the different forms of dating violence develop over time. For example, does psychological abuse precede physical violence? Does physical violence precede sexual aggression? Developmental information would be invaluable in identifying youth at risk for dating violence and to ultimately prevent the occurrence and escalation of violent behavior. To address these questions and gaps in the literature, I propose to conduct a longitudinal study assessing dating violence perpetration and victimization, and modifiable risk and protective factors in adolescents from ethnically and socioeconomically diverse backgrounds. Participants will be recruited from standard and alternative high schools. Dating history, experiences with dating violence (perpetration and victimization), and potential modifiable risk and protective factors will be assessed at baseline, and 1 and 2 years thereafter. A total of 500 participants will be recruited, which will provide sufficient statistical power to achieve the primary aims of this study. The overall objectives of this K23 award are (1) to advance my knowledge of and expand my research into the area of violence prevention, and (2) to provide a sound foundation for developing a dating violence prevention program that will explicitly target identified risk and protective factors. The proposed research study will allow me to apply my current knowledge and skill base to learning the technical and practical issues related to prevention research so I can approach future research endeavors from a truly developmental perspective.